Reduced-pressure wound treatment systems and methods employing microstrain-inducing manifolds

ABSTRACT

Microstrain-inducing manifolds, systems, and methods are presented that involve microstrain-inducing manifolds that include a plurality of shaped projections for creating microstrain. The shaped projections may be tapered projections. A system may include a sealing member for placing over the tissue site, a microstrain-inducing manifold, and a reduced-pressure subsystem that delivers reduced pressure to the sealing member. The reduced pressure causes the shaped projections to create microstrain at the tissue site. Other methods, apparatuses, and systems are also presented.

RELATED APPLICATIONS

This application is a continuation application of U.S. patentapplication Ser. No. 12/639,253, entitled “Reduced-Pressure WoundTreatment Systems and Methods Employing A Microstrain-InducingManifold,” filed Dec. 16, 2009 which claims the benefit, under 35 U.S.C.§119(e), of the filing of U.S. Provisional Patent Application Ser. No.61/140,662, entitled “Reduced-Pressure Wound Treatment Systems andMethods Employing A Microstrain-Inducing Manifold,” filed 24 Dec. 2008,which is incorporated herein by reference for all purposes. Thisapplication is co-pending with U.S. application Ser. No. 12/639,288,filed 16 Dec. 2009, entitled, “Reduced-Pressure Wound Treatment Systemsand Methods Employing Manifold Structures” (VAC.0904US).

BACKGROUND

The present invention relates generally to medical treatment systemsand, more particularly, to reduced-pressure wound treatment systems andmethods employing microstrain-inducing manifolds.

Clinical studies and practice have shown that providing a reducedpressure in proximity to a tissue site augments and accelerates thegrowth of new tissue at the tissue site. The applications of thisphenomenon are numerous, but application of reduced pressure has beenparticularly successful in treating wounds. This treatment (frequentlyreferred to in the medical community as “negative pressure woundtherapy,” “NPWT,” “reduced pressure therapy,” or “vacuum therapy”)provides a number of benefits, which may include faster healing andincreased formulation of granulation tissue.

Negative pressure therapy, or reduced-pressure therapy, has been used topromote healing across a wide range of wound types. Typically, anopen-cell foam is placed directly into the wound bed. A drape is thenused to cover the dressing and seal the wound. The sealing member isthen fluidly coupled to a reduced-pressure therapy unit to providenegative pressure, or reduced pressure, to the wound through the foam.While this approach has produced meaningful results, shortcomings andareas of desired of improvement remain.

BRIEF SUMMARY

Shortcomings with wound care systems and methods are addressed by theillustrative embodiments herein. According to one illustrativeembodiment, a reduced-pressure wound treatment system for treatingtissue on a patient includes a microstrain-inducing manifold fordisposing proximate the tissue that includes a plurality of shapedprojections for creating microstrain within the tissue, a sealing memberfor placing over the tissue and microstrain-inducing manifold andoperable to form a fluid seal over the tissue and microstrain-inducingmanifold, and a reduced-pressure subsystem for delivering a reducedpressure to the sealing member. The shaped projections comprise taperedprojections.

According to another illustrative embodiment, a microstrain-inducingmanifold for treating tissue on a patient includes a plurality of shapedprojections for creating microstrain within the tissue. The shapedprojections comprise tapered projections.

According to another illustrative embodiment, a reduced-pressure woundtreatment system for treating tissue on a patient includes amicrostrain-inducing manifold for disposing proximate the tissue. Themicrostrain-inducing manifold includes a plurality of interconnectednodes. At least one of the interconnected nodes includes at least oneshaped projection for creating microstrain within the tissue. The shapedprojection may be an angled projection. The system further includes asealing member for placing over the tissue and manifold. The sealingmember is operable to form a fluid seal over the tissue andmicrostrain-inducing manifold. The system further includes areduced-pressure subsystem for delivering a reduced pressure to thesealing member.

According to another illustrative embodiment, a microstrain-inducingmanifold for treating tissue on a patient includes a plurality ofinterconnected nodes. At least one of the interconnected nodes includesat least one shaped projection for creating microstrain within thetissue. The shaped projection may be an angled projection.

According to another illustrative embodiment, a method for treatingtissue on a patient includes placing a microstrain-inducing manifoldproximate the tissue of the patient. The microstrain-inducing manifoldincludes a plurality of shaped projections for creating microstrainwithin the tissue. The shaped projections may be tapered projections.The method further includes disposing a sealing member over themicrostrain-inducing manifold and the patient's epidermis; forming afluid seal between the sealing member and the patient's epidermis; andproviding reduced pressure to the microstrain-inducing manifold wherebythe plurality of shaped projections create microstrain within thetissue.

Other features and advantages of the illustrative embodiments willbecome apparent with reference to the drawings and detailed descriptionthat follow.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete understanding of the present invention may be obtainedby reference to the following Detailed Description when taken inconjunction with the accompanying Drawings wherein:

FIG. 1 is a schematic, perspective view of an illustrative, non-limitingembodiment of a reduced-pressure wound treatment system for treating awound on a patient shown over a wound;

FIG. 2 is a schematic, cross-sectional view of a portion of the systemof FIG. 1 taken along line 2-2 in FIG. 1;

FIG. 3A is a schematic, perspective view of an illustrative,non-limiting embodiment of a microstrain-inducing manifold for use intreating a tissue site, such as a wound, on a patient as part of anillustrative, non-limiting embodiment of a reduced-pressure woundtreatment system;

FIG. 3B is an enlarged detail of the perspective view of FIG. 3A;

FIG. 3C is a side view of a portion of an interconnected node and shapedprojection of the microstrain-inducing manifold shown in FIGS. 3A and3B;

FIG. 4A is a schematic, perspective view of an illustrative,non-limiting embodiment of a microstrain-inducing manifold for use intreating a tissue site;

FIG. 4B is a schematic, top view of the microstrain-inducing manifold ofFIG. 4A;

FIG. 5A is a schematic, perspective view of an illustrative,non-limiting embodiment of a microstrain-inducing manifold for use intreating a wound on a patient;

FIG. 5B is an enlarged partial view of the microstrain-inducing manifoldof FIG. 5A;

FIG. 6A is a schematic, perspective view of an illustrative,non-limiting embodiment of a microstrain-inducing manifold for use intreating a wound on a patient as part of an illustrative, non-limitingembodiment of a reduced-pressure wound treatment system;

FIG. 6B is an enlarged partial view of the microstrain-inducing manifoldof FIG. 6A; and

FIG. 7 is a schematic, side view of an illustrative, non-limitingembodiment of a microstrain-inducing manifold.

DETAILED DESCRIPTION

In the following detailed description of the preferred embodiments,reference is made to the accompanying drawings that form a part hereof,and in which is shown, by way of illustration, specific embodiments inwhich the invention may be practiced. These embodiments are described insufficient detail to enable those skilled in the art to practice theinvention, and it is understood that other embodiments may be utilizedand that logical structural, mechanical, electrical, and chemicalchanges may be made without departing from the spirit or scope of theinvention. To avoid detail not necessary to enable those skilled in theart to practice the invention, the description may omit certaininformation known to those skilled in the art. The following detaileddescription is, therefore, not to be taken in a limiting sense, and thescope of the present invention is defined only by the appended claims.

Referring now primarily to FIGS. 1-3B, an illustrative, non-limitingembodiment of a reduced-pressure wound treatment system 100 for treatinga tissue site 103 on a patient is presented. The tissue site 103 may,be, for example, a wound 102, or damaged area of tissue, on a patient.The tissue site 103 may be the bodily tissue of any human, animal, orother organism, including bone tissue, adipose tissue, muscle tissue,dermal tissue, vascular tissue, connective tissue, cartilage, tendons,ligaments, or any other tissue. Unless otherwise indicated, as usedherein, “or” does not require mutual exclusivity. While thereduced-pressure wound treatment system 100 is shown in the context ofthe wound 102, it will be appreciated that the reduced-pressure woundtreatment system 100 may be used to treat many different types of tissuesites 103 and wounds including area wounds, incisions, internal wounds,or other tissue sites. The reduced-pressure wound treatment system 100is shown on the wound 102, which is through the epidermis 104, orgenerally skin, and the dermis 106 and reaching into a hypodermis, orsubcutaneous tissue 108.

The reduced-pressure wound treatment system 100 generally includes asealing member 110, a microstrain-inducing manifold 112, and areduced-pressure subsystem 114. As will be described further below, inoperation the microstrain-inducing manifold 112 induces microstrain andmay be referred to as a microstrain-inducing manifold. Themicrostrain-inducing manifold 112 has a first side 113 and a second,patient-facing side 115.

Among the numerous benefits of the reduced-pressure wound treatmentsystem 100 is the biological response initiated by microstrain withinthe wound 102. Microstrain results from pressure distributed with themicrostrain-inducing manifold 112 to a tissue site 103, such as a woundsurface 105 of the wound 102. It is believed that this action createsareas of cell surface strain, or microdeformation. The cells appear torespond to the strain by expressing special receptors on the surface ofthe cells and turning on genetic pathways in the cells, which promotehealing activities. The healing activities may include increasedmetabolic activity, stimulation of fibroblast migration, increasedcellular proliferation, extra cellular matrix production, and theformation of granulation tissue, as well as a decrease in edema and asubsequent improvement of perfusion at the tissue site 103. With respectto the wound 102, over time, granulation tissue fills the wound 102 andthereby further reduces volume and prepares the wound 102 for finalclosure by secondary or delayed primary intention.

The sealing member 110 is generally formed from a flexible sheet. Thesealing member 110 includes a first surface 120 and a patient-facingsurface 122. The sealing member 110 may be sized so that the sealingmember 110 overlaps the wound 102 in such a manner that a drapeextension 116 extends beyond the peripheral edge of the wound 102.

The sealing member 110 may be formed from any material that provides afluid seal. As used herein, “fluid seal,” or “seal,” means a sealadequate to maintain reduced pressure at a desired site, e.g., a tissuesite, given the particular reduced-pressure source involved. The sealingmember may, for example, be an impermeable or semi-permeable,elastomeric material. “Elastomeric” means having the properties of anelastomer. Elastomeric generally refers to a polymeric material that hasrubber-like properties. More specifically, most elastomers have ultimateelongations greater than 100% and a significant amount of resilience.The resilience of a material refers to the material's ability to recoverfrom an elastic deformation. Examples of elastomers may include, but arenot limited to, natural rubbers, polyisoprene, styrene butadiene rubber,chloroprene rubber, polybutadiene, nitrile rubber, butyl rubber,ethylene propylene rubber, ethylene propylene diene monomer,chlorosulfonated polyethylene, polysulfide rubber, polyurethane, EVAfilm, co-polyester, and silicones. Specific examples of sealing membermaterials include a silicone drape, 3M Tegaderm® drape, acrylic drapesuch as one available from Avery Dennison, or an incise drape.

An attachment member 118 or device may be coupled to the sealing member110. The attachment member 118 is operable to removably couple thesealing member 110 to a patient's epidermis 104. As used herein, theterm “coupled” includes coupling via a separate object and includesdirect coupling. The term “coupled” also encompasses two or morecomponents that are continuous with one another by virtue of each of thecomponents being formed from the same piece of material. Also, the term“coupled” may include chemical, such as via a chemical bond, mechanical,thermal, or electrical coupling. Fluid coupling means that fluid is incommunication between the designated parts or locations. The sealingmember 110 and attachment member 118 work together to form a fluid sealover the patient's epidermis 104. The attachment member 118 may be anymaterial suitable to help couple the sealing member 110 to a patient'sepidermis 104. For example, the attachment member 118 may be apressure-sensitive adhesive, heat-activated adhesive, sealing tape,double-sided sealing tape, paste, hydrocolloid, hydrogel, hooks,sutures, etc.

In the illustrative embodiment, the attachment member 118 is an adhesivelayer 119 coupled to the patient-facing surface 122 of the drapeextension 116. The attachment member 118 may span the entire width or aportion of the patient-facing surface 122 of the sealing member 110.Alternatively, in the case of sealing tape, the attachment member 118may be applied over the entire first surface 120 of the sealing member110, or over the first surface of the drape extensions 116.

The microstrain-inducing manifold 112 is typically positioned betweenthe second, patient-facing surface 122 of the sealing member 110 and thetissue site 103, e.g., the wound 102. The microstrain-inducing manifold112 may be sized to approximate the estimated area of the wound 102,although a larger or smaller size may be used in different applications.In the illustrative embodiment, the microstrain-inducing manifold 112includes a plurality of interconnected nodes 124. The interconnectednodes 124 may have a substantially circular cross-section, but it willbe appreciated that the interconnected nodes 124 may have any suitablecross-section including, but not limited to, triangular, square,rectangular, hexagonal, octagonal, elliptical, etc.

Each interconnected node 124 may include one or more shaped projections126. The shaped projections 126 are operable to create microstrain atthe cellular level within the tissue site 103, e.g., the wound 102.While the illustrative embodiment shows each interconnected node 124having a plurality of shaped projections 126, it will be appreciatedthat some interconnected nodes 124 may be formed to avoid creatingmicrostrains in certain areas. For example, one or more shapedprojections 126 may be formed with a lower profile in a certain area orbe absent all together in certain areas. Moreover, an additionalmanifold with no shaped projections, e.g., a smooth, laminar manifold,may be placed between at least a portion of the shaped projections 126of the microstrain-inducing manifold 112 and a portion of the tissuesite 103 to prevent the creation of strain in a certain area. It isbelieved that avoiding microstrains in certain areas is helpful tooverall patient care. For example, it may be desirable to have amicrostrain-inducing manifold 112 without projections 126 or that doesnot create microstrains in certain areas if a portion of themicrostrain-inducing manifold 112 will lay on top of a vein, an artery,graft(s), objects used for adjunctive treatment or therapy (e.g.,stents), exposed organs (e.g., heart or bowel), etc.

The shaped projections 126 may be substantially the same size.Alternatively, some projections 126 may be larger or smaller thanothers. In one alternative, some shaped projections 126 may have alarger pitch than others, where “pitch” is defined by the angle 128between a reference line 127 formed to have a right angle with alongitudinal axis 129 of the shaped projection 126 as shown in crosssection in FIG. 3C. Each shaped projection 126 has an outer surface 130and a base 132. While the shaped projections 126 in the illustrativeembodiment are conical in shape, it will be appreciated that the shapedprojections 126 may have any suitable shape capable of creating amicrostrain within the wound 102; for example, the shaped projections126 may be substantially cube shaped, pyramid shaped, hemisphericallyshaped, cylindrically shaped, triangularly shaped, cylindrically shapedwith a distal recess, tapered, more elaborately shaped, etc. The shapedprojections 126 are typically angled or tapered from a thick proximalend to a thin distal end or vice versa. In one embodiment, the shapedprojections 126 are formed of the same material as the interconnectednodes 124. Alternatively, at least some of the shaped projections 126may be formed from a different material or the same material type ofmaterial with different properties than the interconnected nodes 124 orthe other shaped projections 126. Via material selection, one maycontrol the stiffness of the interconnected nodes 124 such that greatermicrostrain may be provided in certain areas of the wound 102 versusothers. The interconnected nodes 124, shaped projections 126, and themicrostrain-inducing manifold 112 generally may be formed of a foammaterial or a non-foam material.

The interconnected nodes 124 may be interconnected using a network ofconnecting members 134. For example, the network of connecting members134 may include a plurality of members 136 with each member 136 couplingadjacent interconnected nodes 124 to one another. In the illustrativeembodiment, the members 136 have a substantially circular cross-section;however, it will be appreciated that the members 136 may have anysuitable cross-section, including, but not limited to, triangular,square, rectangular, hexagonal, octagonal, elliptical, etc. In addition,as will be discussed below, the connecting members 134 may be configuredsuch that the microstrain-inducing manifold 112 behaves anisotropicallywhen subjected to a reduced pressure.

The interconnected nodes 124, connecting members 134, and shapedprojections 126 are arranged such that the microstrain-inducing manifold112 includes a plurality of flow channels 140 (FIG. 3B) or pathwaysbetween the interconnected nodes 124. The flow channels 140 improvedistribution of fluids provided to and removed from the area of tissuearound the microstrain-inducing manifold 112. Thus, themicrostrain-inducing manifold 112 is operable to assist in applyingreduced pressure to, delivering fluids to, or removing fluids from atissue site 103. Moreover, the design of microstrain-inducing manifold112 helps to avoid painful removal caused by in-growth, i.e., whengrowth of granulation tissue occurs into a manifold, and allows foreasier removal from the tissue site 103.

The microstrain-inducing manifold 112 may be formed from any suitablematerial. By way of example only, and without limitation, themicrostrain-inducing manifold 112 may be formed from an elastomer, abioabsorbable/biodegradable polymer, etc. In addition, the manifoldmaterial may itself be, or may be combined with, a radio opaque materialor a UV florescent material such that the wound 102 may be scanned withan X-ray or UV light in order to determine whether or not any remnantsof the microstrain-inducing manifold 112 remain in the wound 102 afterefforts have been made to remove the microstrain-inducing manifold 112from the wound 102. Additionally, the shaped projections 126, ormicrostrain-inducing manifold 112 as a whole, may be coated with a drug(e.g., an anticoagulant), an antimicrobial agent (e.g., silver orcopper), a hydrophilic material, etc. Optionally, themicrostrain-inducing manifold 112 may also be formed with additionalcomponents, e.g., a delivery tube (not shown), whereby drugs orantimicrobial agents may be delivered to the wound 102 through themicrostrain-inducing manifold 112.

The microstrain-inducing manifold 112 may be formed by any suitableprocess, including, but not limited to, micromolding, injection molding,casting, etc. The shaped projections 126 may be formed to besubstantially integral with corresponding interconnected nodes 124 ormay be coupled to corresponding interconnected nodes 124 by any suitabletechnique, including, but not limited to, mechanical fasteners, welding(e.g., ultrasonic or RF welding), bonding, adhesives, cements, etc.

The microstrain-inducing manifold 112 may include numerous devices forcreating point pressure or otherwise inducing microstrain. In oneillustrative, non-limiting embodiment, the microstrain-inducing manifold112 includes limited contact points with the tissue site 103. Thecontact points contribute to the inducement of microstrain at the tissuesite 103. Thus, in one illustrative, non-limiting embodiment, themicrostrain-inducing manifold 112 adjacent the tissue site 103 may havea projection surface area of X cm² associated with the second,patient-facing side, and yet the portion of the microstrain-inducingmanifold 112 directly impinging on the tissue site 103 may be less than40 percent of the surface area X (40% X). As used herein, “projectionsurface area” means the area that a general projection of an item wouldmake on a flat surface.

In another illustrative, non-limiting embodiment, themicrostrain-inducing manifold 112 adjacent the tissue site 103 may havea projection surface area of X cm² associated with the second,patient-facing side, and yet the portion of the microstrain-inducingmanifold 112 directly impinging on the tissue site 103 may be less than30 percent of the surface area X (30% X). In another illustrative,non-limiting embodiment, the microstrain-inducing manifold 112 adjacentthe tissue site 103 may have a projection surface area of X cm²associated with the second, patient-facing side, and yet the portion ofthe microstrain-inducing manifold 112 directly impinging on the tissuesite 103 may be less than 20 percent of the surface area X (20% X). Inone illustrative, non-limiting embodiment, the microstrain-inducingmanifold 112 adjacent the tissue site 103 may have a projection surfacearea of X cm² associated with the second, patient-facing side, and yetthe portion of the microstrain-inducing manifold 112 directly impingingon the tissue site 103 may be less than 10 percent of the surface area X(10% X). In one illustrative, non-limiting embodiment, themicrostrain-inducing manifold 112 adjacent the tissue site 103 may havea projection surface area of X cm² associated with the second,patient-facing side, and yet the portion of the microstrain-inducingmanifold 112 directly impinging on the tissue site 103 may be less than5 percent of the surface area X (5% X).

In still another illustrative, non-limiting embodiment, themicrostrain-inducing manifold 112 adjacent the tissue site 103 may havea projection surface area of X cm² associated with the second,patient-facing side, and yet the portion of the microstrain-inducingmanifold 112 directly impinging on the tissue site 103 may be less than2 percent of the surface area X (2% X). In one illustrative,non-limiting embodiment, the microstrain-inducing manifold 112 adjacentthe tissue site 103 may have a projection surface area of X cm²associated with the second, patient-facing side, and yet the portion ofthe microstrain-inducing manifold 112 directly impinging on the tissuesite 103 may be less than 1 percent of the surface area X (1% X). In oneillustrative, non-limiting embodiment, the microstrain-inducing manifold112 adjacent the tissue site 103 may have a projection surface area of Xcm² associated with the second, patient-facing side, and yet the portionof the microstrain-inducing manifold 112 directly impinging on thetissue site 103 may be less than 0.5 percent of the surface area X (0.5%X).

In one illustrative, non-limiting embodiment, the microstrain-inducingmanifold 112 adjacent the tissue site 103 may have a projection surfacearea of X cm² associated with the second, patient-facing side, and yetthe portion of the microstrain-inducing manifold 112 directly impingingon the tissue site 103 may be less than 0.2 percent of the surface areaX (0.2% X). Referring to FIG. 2, the microstrain-inducing manifold 112adjacent to tissue site 103 103, e.g., wound surface 105, may cover thewound surface 105, and may have a projection surface area X, and yet theportion of microstrain-inducing manifold 112 directly impinging on thewound surface 105 may only be 0.2 percent of X. Referring to FIG. 3C, itshould be understood that the impinging portion may only be a portion ofan outer surface 130 of each of the plurality of shaped projections 126.

The microstrain-inducing manifold 112 may be disposed proximate thewound 102 such that the interconnected nodes 124 engage the woundsurface 105. In one illustrative embodiment, the microstrain-inducingmanifolds 112 are stacked on top of one another to substantially fillthe wound 102. However, it will be appreciated that a singlemicrostrain-inducing manifold 112 may be employed or a multi-layermicrostrain-inducing manifold may also be formed and used. Themicrostrain-inducing manifold 112 may be formed from a singleinterconnected node 124 with a shaped projection 126; multipleindependent interconnected nodes 124 with shaped projections 126; or agroup of interconnected nodes 124, which include shaped projections 126,that are interconnected with the connecting members 134.

It will also be appreciated that a single microstrain-inducing manifold112 may be rolled up or folded over itself in order to fill the wound102. Furthermore, it will be appreciated that a singlemicrostrain-inducing manifold 112 may be loaded into the wound 102 andan additional manifold placed atop the manifold 112. Examples ofadditional manifolds that may be placed atop the microstrain-inducingmanifold 112 include, without limitation, devices that have structuralelements arranged to form flow channels, cellular foam such as open-cellfoam, porous tissue collections, and liquids, gels and foams thatinclude or cure to include flow channels.

Referring again to FIG. 1, the reduced-pressure subsystem 114 includes areduced-pressure source 142, which may take many different forms. Thereduced-pressure source 142 provides reduced pressure as a part of thereduced-pressure wound treatment system 100. As used herein, “reducedpressure” generally refers to a pressure less than the ambient pressureat a tissue site that is being subjected to treatment. In most cases,this reduced pressure will be less than the atmospheric pressure atwhich the patient is located. Alternatively, the reduced pressure may beless than a hydrostatic pressure at the tissue site. Reduced pressuremay initially generate fluid flow in the microstrain-inducing manifold112, a conduit 150, and proximate the tissue site 103. As thehydrostatic pressure around the tissue site 103 approaches the desiredreduced pressure, the flow may subside, and the reduced pressure may bemaintained. Unless otherwise indicated, values of pressure stated hereinare gauge pressures. The reduced pressure delivered may be static ordynamic (patterned or random) and may be delivered continuously orintermittently. Although the terms “vacuum” and “negative pressure” maybe used to describe the pressure applied to the tissue site, the actualpressure applied to the tissue site may be more than the pressurenormally associated with a complete vacuum. Consistent with the useherein, an increase in reduced pressure or vacuum pressure typicallyrefers to a relative reduction in absolute pressure.

The reduced-pressure subsystem 114 provides reduced pressure. Thereduced-pressure subsystem 114 includes a reduced-pressure source 142that may be any source of a reduced pressure, such a vacuum pump, wallsuction, etc. While the amount and nature of reduced pressure applied toa tissue site will typically vary according to the application, thereduced pressure will typically be between −5 mm Hg and −500 mm Hg.Pressure may be applied to the microstrain-inducing manifold 112 inother ways as well; for example, a pressure wrap may be used.

In the illustrative embodiment of FIG. 1, the reduced-pressure source142 is shown having a battery compartment 144 and a canister region 146with windows 148 providing a visual indication of the level of fluidwithin canister 146. An interposed membrane filter, such as hydrophobicor oleophobic filter, may be interspersed between the conduit 150, ortubing, and the reduced-pressure source 142.

The reduced pressure supplied by the reduced-pressure source 142 isdelivered through the conduit 150 to a reduced-pressure interface 152,which may be an elbow port 154. In one illustrative embodiment, the port154 is a TRAC® technology port available from Kinetic Concepts, Inc. ofSan Antonio, Tex. The reduced-pressure interface 152 allows the reducedpressure to be delivered to the sealing member 110 and realized withinan interior portion of sealing member 110 as well as themicrostrain-inducing manifold 112. In this illustrative embodiment, theport 154 extends through the sealing member 110 to themicrostrain-inducing manifold 112.

In use, the reduced-pressure wound treatment system 100 may be appliedto a patient's epidermis 104 over the tissue site 103, e.g., wound 102.The microstrain-inducing manifold 112 may be disposed proximate thetissue site 103, e.g., disposed within the wound 102, or may overlay aportion of the wound 102. The sealing member 110 may be placed over thetop of the microstrain-inducing manifold 112 such that drape extensions116 extend beyond the periphery of the wound 102. The drape extensions116 are secured to the patient's epidermis 104 (or a gasket member, suchan additional piece of over drape surrounding the wound edges) by theattachment member 118 in order to form a fluid seal over the wound 102.As used herein, reference to forming a fluid seal with the patient'sepidermis shall be deemed to also include forming a seal with a gasketproximate the wound 102.

The reduced-pressure interface 152 is applied, if not already installed,and the conduit 150 fluidly coupled at one end to the reduced-pressureinterface 152. The other end of the conduit 150 is fluidly coupled tothe reduced-pressure source 142. The reduced-pressure source 142 may beactivated such that reduced pressure is delivered to the sealing member110 and microstrain-inducing manifold 112. The reduced pressure providesreduced-pressure treatment to the tissue site 103, removes fluids, andmay force the shaped projections 126 of the microstrain-inducingmanifold 112 against the wound 102 such that they create a microstrainat the cellular level within the wound 102. As previously suggested, themicrostrain may promote cellular proliferation, formation of granulartissue, and other beneficial effects. Alternatively, themicrostrain-inducing manifold 112 may be placed proximate the tissuesite 103 and then pressure may be applied by using a wrap over themicrostrain-inducing manifold 112 or other source of pressure.

Referring now primarily to FIGS. 4A and 4B, an illustrative,non-limiting embodiment of a microstrain-inducing manifold 212 for useas part of a reduced-pressure wound treatment, such as thereduced-pressure wound treatment system 100 in FIG. 1, is shown. Themicrostrain-inducing manifold 212 includes interconnected nodes 224,which include shaped projections 226 extending from the interconnectednodes 224. In the illustrative embodiment, the shaped projections 226are conical in shape; however, it will be appreciated that the shapedprojections 226 may be any suitable shape capable of creatingmicrostrain within a wound as previously discussed. Moreover, while eachinterconnected node 224 of the illustrative embodiment includes twoprojections 226 (one directed up and one directed down for theorientation shown in FIG. 4A), it will be appreciated that any number ofprojections 224 may extend from each interconnected node 224 or thatsome of the interconnected nodes 224 may have no projections 224. Also,in the illustrative embodiment, each projection 226 extendssubstantially normal from a corresponding interconnected node 224, butit will be appreciated that each projection 226 may extend from thecorresponding interconnected node 224 at any angle.

The interconnected nodes 224 are spaced apart and interconnected by anetwork of connecting members 234 as clearly shown in FIG. 4B. Thenetwork of connecting members 234 includes a plurality of curved members236. A plurality of flow channels 240 are formed between theinterconnected nodes 224 and members 236. The members 236 have curvedsurfaces 290 that are curved in a cooperative manner with one another orwith the radius of one or more corresponding interconnected nodes 224such that when the microstrain-inducing manifold 212 is subjected to areduced pressure, the microstrain-inducing manifold 212 collapses(partially or fully) in two directions (e.g., along the x-axis 286 andy-axis 288) but not at all or to a lesser extent in a third direction(e.g., the z-axis 284). As the microstrain-inducing manifold 212collapses, each curved surface 290 of each member 236 abuts orapproaches a curved surface 290 of an adjacent member 236 or at leastone corresponding interconnected node 224. This may be particularlyadvantageous if the reduced-pressure wound treatment system isconfigured to assist in drawing the wound together during reducedpressure therapy.

Referring now primarily to FIGS. 5A and 5B, an illustrative,non-limiting embodiment of a manifold structure 412, which is a form ofa microstrain-inducing manifold, is presented. The manifold structure412 is for use with a reduced-pressure wound treatment system, such asthe reduced-pressure wound treatment system 100 of FIG. 1, is shown. Themanifold structure 412 includes one or more longitudinal members 456.The longitudinal members 456 may be coupled in a spaced relationship bylateral connecting members 460. The lateral connecting members 460 maybe coupled to the longitudinal members 456. The longitudinal members 456and lateral connecting members 460 are shown with circularcross-sections, but it should be appreciated that the longitudinalmembers 456 and lateral connecting members 460 may have any suitablecross-sectional shape. While reference is made to longitudinal andlateral members, the members 456, 460 need not be orthogonal but mayhave other relative angles.

Each longitudinal member 456 of the manifold structure 412 includes oneor more shaped projections 426 for creating a microstrain within awound. The longitudinal members 456 and shaped projections 426 arearranged such that the manifold structure 412 includes a plurality offlow channels 440 or pathways between adjacent longitudinal members 456or between projections 426. The flow channels 440 facilitatedistribution of fluids provided to and removed from the area of tissuearound the manifold structure 412. It should be understood that anycombination of longitudinal members 456 and lateral members 460 may beused. For example, the manifold structure 412 may be formed by alongitudinally connected group of longitudinal members 456 withprojections 426. There are eight such longitudinal groups shown in FIG.5A, and while shown with the lateral connecting members 460, the lateralconnecting members 460 may be omitted in some embodiments. Moreover,while only lateral connecting members 460 are shown on the ends, itshould be understood that any number of permutations are possible, andlateral members 460 may be distributed at various locations between thelongitudinal members 456.

In the illustrative embodiment, each shaped projection 426 projectssubstantially normal from the corresponding longitudinal member 456. Asused here, “normal” is a vector which perpendicular to that surface. Fora non-flat surface, the normal vector may be taken at a point and is thesame as a normal to the tangent plane at that point. It should beappreciated, however, that each shaped projection 426 may project at anyangle relative to the corresponding longitudinal member 456. Each shapedprojection 426 may include a columnar body 427, which has a first outerdiameter (D₁), and an enlarged member 429, which has a second outerdiameter (D₂). Each enlarged member 429 is positioned at the distal endof an associated columnar body 427. Each columnar body 429 may have anyshape, e.g., the cross-section may be a circular, square, elliptical,irregular, etc., and may vary along its longitudinal dimension. Theenlarged member 429 may be a spherical member as shown or may take anyother shape, such as rounded cylindrical member, a cubical member, or anirregular shape. The second outer diameter (D₂) of the enlarged member429 is greater than the first outer diameter (D₁) of the columnar body427, i.e., D₂>D₁. In this regard, the shaped projections 426 may beconsidered to be tapered from a larger distal end to a smaller proximalend.

Each shaped projection 426 may have any suitable shape capable ofcreating a microstrain within the wound when the shaped projection 426impinges upon the wound. Additionally, in the illustrative embodiment,the shaped projections 426 have substantially equal heights, but it willbe appreciated that the shaped projections 426 may have varying heightsalong each longitudinal member 456 or among the plurality oflongitudinal members 456. Also, it will be appreciated that certainportions of certain longitudinal members 456 may not have shapedprojections 426 such that microstrain is not provided to certain areaswithin the wound. As with the microstrain-inducing manifolds previouslydiscussed, the manifold structure 412 may be formed using any suitableprocess, including, but not limited to, micromolding, injection molding,casting, etc. The shaped projections 426 may be formed to besubstantially integral with corresponding longitudinal members 456 ormay be coupled to corresponding longitudinal members 456 by any suitabletechnique including, but not limited to, mechanical fasteners, welding(e.g., ultrasonic or RF welding), bonding, adhesives, cements, etc.

In use, the manifold structure 412 is placed proximate the tissue site,e.g., wound, and a sealing member is deployed over the manifoldstructure 412 and tissue site. Reduced pressure may then be applied oralternatively a direct pressure may be applied. In some embodiments,e.g., embodiment with widely spaced lateral members 460, when themanifold structure 412 is subjected to a reduced pressure, the manifoldstructure 412 may behave anisotropically. In other words, when themanifold structure 412 is subjected to a reduced pressure, in additionto the shaped projections 426 being forced into the wound to createmicrostrain, the longitudinal members 456 may move laterally towardseach other. Each longitudinal member 456 move closer to an adjacentlongitudinal member 456 than the adjacent longitudinal members 456 wereprior to the introduction of the reduced pressure. At the same time, themanifold structure 412 does not substantially contract in a directionsubstantially parallel to the longitudinal members 456.

If the lateral connecting members 460 are omitted, even furthercontraction may be possible. The manifold structure 412 may deform morein a direction substantially perpendicular to the longitudinal members456 (as illustrated by arrows 458 in FIG. 5A) without a proportionaldeformation in the direction parallel with the longitudinal members 456.The deformation is typically within the same plane. This may beadvantageous if the system employs other components, such as ananisotropic drape or another manifold, for drawing the wound togetherduring reduced pressure therapy wherein the illustrative manifoldstructure 412 contracts in a manner complimentary therewith. If spacedlateral connecting members 460 are used in sufficient number, verylittle contraction may take place. In an alternative embodiment, themanifold structure 412 is configured such that some longitudinal members456 are arranged substantially perpendicular to other longitudinalmembers 456 whereby the manifold structure 412 partially contracts, orcontracts in a more limited manner, in two directions within the sameplane when subjected to a reduced pressure.

Referring now primarily to FIGS. 6A and 6B, another illustrative,non-limiting embodiment of a microstrain-inducing manifold 512 for usewith a reduced-pressure wound treatment system, such as areduced-pressure wound treatment system 100 (FIG. 1), is shown. Themicrostrain-inducing manifold 512 includes a mat 558, or base, fromwhich a plurality of shaped projections 526 extend. The mat 558 has afirst side 513 and a second, patient-facing side 515. In theillustrative embodiment, the shaped projections 526 are tapered and inparticular are substantially conical in shape, but it will beappreciated that the projections 526 may have any suitable shape capableof creating microstrain within the wound. Also, while the illustrativeembodiment shows the projections 526 extending substantially normal,i.e., perpendicular, from the mat 558, it will be appreciated that theprojections 526 may extend from the mat 558 at any suitable angle.Furthermore, in the illustrative embodiment, the projections 526 havesubstantially equal heights, but the mat 558 may include projections 526of varying heights. Portions of the mat 558 may not have any projectionssuch that microstrain is not provided to certain areas within the wound.Additionally, the stiffness of the shaped projections 526 and pitch ofthe shaped projections 526 may vary along the mat 558 such that themicrostrain created by the projections 526 may be greater in certainareas of the wound versus other areas.

The shaped projections 526 may be formed as integral portions of the mat558 or coupled to the mat 558 by any suitable techniques, including butnot limited to mechanical fasteners, welding (e.g., ultrasonic or RFwelding), bonding, adhesives, cements, etc. The mat 558 may alsoincludes a plurality of apertures 560 (FIG. 6B) disposed between theprojections 526 to improve the distribution of fluids provided to andremoved from the area of tissue around the microstrain-inducing manifold512. In an alternative embodiment, the shaped projections 526 may beformed from a modified honey on the mat 558. The honey may be modifiedso that it is solid or partially solid and retains its shape for atleast a certain amount of time whilst engaging the wound.Advantageously, the honey may act as an antimicrobial agent and may beabsorbed by the patient after a period of time. Other dissolvablesubstances may be used as well.

In operation, the microstrain-inducing manifold 512 is typically placedproximate the tissue site with the second, patient-facing side 515facing the patient and covered with a sealing member. Reduced pressureis then delivered to the microstrain-inducing manifold 512. Whensubjected to a reduced pressure, the microstrain-inducing manifold 512impinges on the wound whereby the shaped projections 526 createmicrostrain within the wound. Additionally, exudate and other fluidspass through the mat 558 via the apertures 560. Also, in some instances,it may be desirable to avoid increasing microstrain within the wound viathe shaped projections 526. In such an instance, themicrostrain-inducing manifold 512 may be inverted such that the firstside 513 of the mat 558 is placed against the wound and the shapedprojections 526 extend towards the sealing member (not shown). Thus, themicrostrain-inducing manifold 512 may assist in perfusion and fluidremoval (via the apertures 560) without also increasing microstrainwithin the wound via the shaped projections 526.

Referring now primarily to FIG. 7, an illustrative, non-limitingembodiment of a microstrain-inducing manifold member 624 for use with areduced-pressure wound treatment system, such as the reduced-pressurewound treatment system 100 in FIG. 1, is shown. A microstrain-inducingmanifold may be formed by a plurality of microstrain-inducing manifolds624. Each microstrain-inducing manifold member 624 has one or moreshaped projections 626 extending from a surface 631. Unlike thereduced-pressure wound treatment system 100 of FIGS. 1-3B, themicrostrain-inducing manifold members 624 are not interconnected by anetwork of connecting members. Rather, a plurality ofmicrostrain-inducing manifold members 624 may be poured into a woundwhereby they work together to form the microstrain-inducing manifold inthe wound (in situ) and whereby the shaped projections 626 of themicrostrain-inducing manifold members 624 contact the wound to createmicrostrain therein. The plurality of microstrain-inducing manifoldmembers 624 may fill the entire wound. Alternatively, the plurality ofmicrostrain-inducing manifold members 624 may partially fill the wound,and, optionally, an alternative manifold may be placed atop themicrostrain-inducing manifold members 624 to fill the wound.

In another alternative, the microstrain-inducing manifold members 624may have a coating of material that allows the microstrain-inducingmanifold members 624 to fuse or sinter in situ to one another and form asingle, integral manifold. Non-limiting examples of coatings include thefollowing: any water soluble, swellable, or softenable material,including polymers such as poly vinyl alcohol and its copolymer,polyvinyl pyrrolidone and its copolymers, polyethylene oxide and itscopolymers, polypropylene oxide and its copolymers, hydroxyl, carboxyl,and sulphonyl containing polymers (e.g., hydroxyl ethyl acrylate,carboxyl methyl cellulose, acrylamido methyl propane sulphonic acid andits salts), alginates, gums (e.g. xanthan and guar), other hydrogels andhydrocolloids.

Although the present invention and its advantages have been disclosed inthe context of certain illustrative, non-limiting embodiments, it shouldbe understood that various changes, substitutions, permutations, andalterations can be made without departing from the scope of theinvention as defined by the appended claims. It will be appreciated thatany feature that is described in a connection to any one embodiment mayalso be applicable to any other embodiment.

We claim:
 1. A reduced-pressure system for treating a tissue site, thesystem comprising: a manifold having a plurality of shaped projectionscoupled in spaced relationship to form flow channels, wherein each ofthe shaped projections comprises a contact point adapted to createmicrostrain within the tissue site; a sealing member adapted to coverthe manifold to form a fluid seal over the manifold; and areduced-pressure subsystem adapted to deliver a reduced pressure to themanifold.
 2. The system of claim 1, wherein the manifold furthercomprises a plurality of interconnected nodes, and each shapedprojection extends from one of the interconnected nodes.
 3. The systemof claim 2, wherein the interconnected nodes are coupled by connectingmembers.
 4. The system of claim 3, wherein the connecting members couplethe nodes into the spaced relationship.
 5. The system of claim 1,wherein at least one of the shaped projections is a right circular cone.6. The system of claim 1, wherein at least one of the shaped projectionshas a first pitch and at least one other of the shaped projections has asecond pitch and wherein the first pitch is greater than the secondpitch.
 7. The system of claim 1, wherein the manifold is adapted todeform more in a first direction than in a second direction whensubjected to the reduced pressure.
 8. The system of claim 7, wherein thefirst direction and the second direction are substantially coplanar. 9.The system of claim 1, wherein the manifold is at least partially coatedwith a drug.
 10. The system of claim 1, wherein the manifold is at leastpartially coated with an antimicrobial material.
 11. The system of claim1, wherein at least one of the shaped projections is formed from abioabsorbable material.
 12. The system of claim 1, wherein at least aportion of the manifold is coated with a hydrophilic material.
 13. Thesystem of claim 1, wherein at least one of the shaped projections has afirst stiffness and at least one other of the shaped projections has asecond stiffness and the first stiffness is greater than the secondstiffness.
 14. The system of claim 1, wherein at least one of the shapedprojections has a first height and at least one other of the shapedprojections has a second height and the first height is greater than thesecond height.
 15. A manifold for treating a tissue site, the manifoldcomprising a plurality of nodes interconnected in a spaced relationshipto form flow channels, wherein each of the nodes comprises one or morecontact points adapted to create microstrain within the tissue site. 16.The manifold of claim 15, further comprising a plurality of connectingmembers, each connecting member having at least one of the nodes coupledto an end of the connecting member.
 17. The manifold of claim 15,further comprising a plurality of connecting members, each connectingmember having at least one of the nodes coupled to each end of theconnecting member, each connecting member also having a length adaptedto position adjacent nodes in the spaced relationship.
 18. Amicrostrain-inducing manifold for disposing proximate the tissue, themicrostrain-inducing manifold comprising a plurality of interconnectednodes, at least one of the interconnected nodes including at least oneshaped projection extending outwardly from the node for creatingmicrostrain within the tissue, wherein the at least one shapedprojection comprises an angled projection having at least one point. 19.The microstrain-inducing manifold of claim 18, further comprising aplurality of connecting members, each connecting member having at leastone of the interconnected nodes coupled to an end of the connectingmember.
 20. The microstrain-inducing manifold of claim 18, furthercomprising a plurality of connecting members, each connecting memberhaving at least one of the interconnected nodes coupled to each end ofthe connecting member, each connecting member also having a lengthpositioning adjacent interconnected nodes in a spaced relationship. 21.A manifold adapted to induce microstrain in a tissue site, the manifoldcomprising: a first node; a second node interconnected to the firstnode; a first contact point coupled to the first node; and a secondcontact point coupled to the second node; wherein the first contactpoint and the second contact point are coupled in a spaced relationshipto form a flow channel between the first node and the second node, andthe first contact point and the second contact point are adapted toinduce microstrain in the tissue site.
 22. The manifold of claim 21,wherein the first contact point is integrally formed with the firstnode.
 23. The manifold of claim 21, wherein the first contact point isformed by a projection extending from the first node.
 24. The manifoldof claim 21, wherein the first contact point is formed by a taperedprojection extending from the first node.
 25. The manifold of claim 21,further comprising a third contact point coupled to the first node. 26.The manifold of claim 21, wherein the first node and the second node arespaced apart by a connecting member.